RELATION BETWEEN CYCLONE EVOLUTION AND FETCH ASSOCIATED WITH EXTREME WAVE EVENTS IN THE SOUTH ATLANTIC OCEAN

Extreme wave generation in middle and high latitudes is mainly associated with extratropical cyclones. The wave generation process depends on the size and orientation of the fetch associated with each cyclone, which is usually not taken into account in traditional statistical approaches. A better understanding of the combined effect of the fetch orientation, displacement and position within the extratropical cyclone can contribute with more accurate wave hindcasts and forecasts, which are crucial to marine operations. The main goal of this work is to investigate the fetch patterns and configurations associated with extratropical cyclones that promote extreme wave events in the westem portion of the South Atlantic Ocean. Cyclones are tracked using an obj ective algorithm and linked to winter extreme Hs events in 10 years of ERA5. The results show the occurrence of 11.4 +/- 2.8 storms per winter associated with extreme waves within the domain. Among these extreme events, the maximum and mean Hs was 10.3m and 6.1m respectively. The analysis of the fetch evolution during the lifecycle of the cyclones associated with the 10 most extreme events showed that the suiface winds present its maximum usually 12h to 24h before the maximum Hs. The spatial pattern of the most severe events shows the development of a large fetch along the continental shelf, usually within the cold sector ofthe cyclone.